Camshaft phasers for varying the timing of valves in internal combustion engines are well known. A typical phaser comprises a stator that is connected with the cam drive system driven by the engine crankshaft and a rotor within the stator connected to the camshaft. The phaser is able to vary the rotary position of the rotor with respect to the stator and thus to vary the valve timing imposed on the camshaft with respect to the crankshaft and pistons.
A prior art camshaft phaser is closed by a threaded metallic plug and an O-ring that seals on a tapered face just inside the bore. The threaded plug is screwed into a threaded cover. The plug is torqued to a required specification, but the torque level is expected to stay above the minimum required specification during thermal cycling, otherwise the plug could loosen and disengage during the life of the engine. A loosened plug or an opened phaser could cause unacceptable leakage negatively effecting operation of the phaser, a failure of the drive belt, unacceptable loss of engine oil pressure, and external oil leaks.
What is needed in the art is an improved closure assembly for a camshaft phaser wherein a plug or cap is sealingly retained in a phaser opening without threads or torquing and no compromise in retention capability during use of the phaser.
It is a principal object of the present invention to prevent disengagement and leakage of a closing plug or cap on a camshaft phaser.